Pressure probes and pressure measurements in airflow

ABSTRACT

In an embodiment, the present disclosure pertains to a pressure probe. In some embodiments, the pressure probe includes a tube having an output end, an internal passage, an axial run, and pressure orifices axially aligned along a downstream side of the axial run. In some embodiments, the pressure orifices are in communication with the output end through the internal passage and an upstream side of the axial run that is opposite from the downstream side of the axial run and does not include a pressure orifice. Additionally, in some embodiments, the downstream side is perpendicular to airflow.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/860,087, filed Jan. 2, 2018. U.S. patent application Ser. No.15/860,087 is incorporated herein by reference.

TECHNICAL FIELD

This application is directed, in general, to pressure probes andmeasuring pressure in airflow and more specifically to measuring airpressure in the varying airflow of climate control systems.

BACKGROUND

This section provides background information to facilitate a betterunderstanding of the various aspects of the disclosure. It should beunderstood that the statements in this section of this document are tobe read in this light, and not as admissions of prior art.

Heating, ventilating and air conditioning (HVAC) systems can be used toregulate the environment within an enclosed space. Typically, an airblower is used to pull air from the enclosed space into the HVAC systemthrough ducts and push the air back into the enclosed space throughadditional ducts after conditioning the air (e.g., heating, cooling ordehumidifying the air). Various types of HVAC systems may be used toprovide conditioned air for enclosed spaces. For example, some HVACunits are located on the rooftop of a commercial building. Theseso-called rooftop units, or RTUs, typically include one or more blowersand heat exchangers to heat and/or cool the building, and baffles tocontrol the flow of air within the RTU. Some RTUs also include anair-side economizer that allows to selectively provide fresh outside airto the RTU or to recirculate exhaust air from the building back throughthe RTU to be cooled or heated again.

When the enthalpy of the fresh air is less than the enthalpy of therecirculated air, conditioning the fresh air may be moreenergy-efficient than conditioning the recirculated air. In this casethe economizer may exhaust a portion of the stale air and replace thevented air with outside air. When the outside air is both sufficientlycool and sufficiently dry it may be possible that no additionalconditioning of the outside air is needed. In this case the economizermay draw a sufficient quantity of outside air into the building toprovide all the needed cooling. In some installations an energy recoveryventilator (ERV) may be used to pre-condition the fresh air demanded bythe RTU. The ERV may include, e.g., an enthalpy exchange zone totransfer heat and/or humidity between an incoming fresh air stream andan outgoing exhaust air stream. The enthalpy exchange zone can includeone or multiple enthalpy wheels. ERVs are typically equipped withfresh-air and return air filters that allow energy recovery from areas,such as kitchens and smoking area, that have a high level ofcontaminants but can still benefit from fresh-air.

HVAC systems may rely on pressures sensors installed in airflow ducts tomonitor and/or control system conditions. These sensors can malfunctionand give inaccurate pressure readings for example due to dustaccumulation and clogging of the probe.

SUMMARY

In an example a pressure probe includes a tube having an output end, aninternal passage, an axial run and pressure orifices axially alignedalong a downstream side of the axial run and in communication with theoutput end through the internal passage. According to an aspect anupstream side of the axial run opposite from the downstream side of theaxial run does not have a pressure orifice.

An example climate control system includes a structure forming anairflow channel, a unit disposed in the structure across which airflowpasses in a downstream direction and a pressure sensor having a firstpressure probe positioned in the airflow channel upstream of the unitand a second pressure probe positioned in the airflow channel downstreamof the unit, where each of the first and the second pressure probesincludes a tube having an output end, an internal passage, an axial runand pressure orifices axially aligned along a downstream side of theaxial run and the axial run is positioned laterally across the airflowchannel with the downstream side of the axial run and the pressureorifices oriented in the downstream direction.

An example method of monitoring a condition of a unit in a climatecontrol system includes obtaining differential static pressure data ofan airflow passing in a downstream direction across a unit disposed inan airflow channel of a climate control system, the differential staticpressure data obtained by a first pressure probe positioned upstream ofthe unit and a second pressure probe positioned downstream of the unitand determining a unit condition based on the obtained differentialstatic pressure data; where each of the first and the second pressureprobes includes a tube having an output end, an internal passage, anaxial run and pressure orifices axially aligned along a downstream sideof the axial run and the axial run is positioned laterally across theairflow channel with the downstream side of the axial run and thepressure orifices oriented in the downstream direction.

This summary is provided to introduce a selection of concepts that arefurther described below in the detailed description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofclaimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with standard practice in the industry, variousfeatures are not drawn to scale. In fact, the dimensions of variousfeatures may be arbitrarily increased or reduced for clarity ofdiscussion. As will be understood by those skilled in the art withbenefit of this disclosure, elements and arrangements of the variousfigures can be used together and in configurations not specificallyillustrated without departing from the scope of this disclosure.

FIG. 1 illustrates an example pressure probe according to one or moreaspects of the disclosure.

FIG. 2 is a cut-away view along the line 2-2 of FIG. 1.

FIG. 3 illustrates an example pressure probe according to one or moreaspects of the disclosure.

FIG. 4 illustrates an example climate control system according to one ormore aspects of the disclosure.

FIG. 5 illustrates a flow diagram of an example method of monitoringaccording to one or more aspects of the disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof various embodiments. Specific examples of components and arrangementsare described below to simplify the disclosure. These are, of course,merely examples and are not intended to be limiting. In addition, thedisclosure may repeat reference numerals and/or letters in the variousexamples. This repetition is for the purpose of simplicity and clarityand does not in itself dictate a relationship between the variousembodiments and/or configurations discussed.

As used herein, the terms connect, connection, connected, in connectionwith, and connecting may be used to mean in direct connection with or inconnection with via one or more elements. Similarly, the terms couple,coupling, coupled, coupled together, and coupled with may be used tomean directly coupled together or coupled together via one or moreelements. Terms such as up, down, top and bottom and other like termsindicating relative positions to a given point or element may beutilized to more clearly describe some elements.

FIG. 1 illustrates and an example of a pressure probe, generally denotedby the numeral 10, in accordance to one or more aspects of thisdisclosure. FIG. 2 is a section view along the line 2-2 of FIG. 1.Pressure probe 10 is constructed of a tube 12 having an output end 14, aterminal end 16, a plurality of pressure orifices 18, and an internalpassage 15 in communication with the output end 14 and the plurality ofpressure orifices 18. The plurality of pressure orifices 18 are axiallyaligned and spaced apart along an axial run 20 of the tube 12. Thepressure orifices 18 are formed along the axial run 20 to obtain anaverage static pressure measurement in irregular airflow. The pressureorifices may be equally spaced from one another. The pressure probe 10is operable in high and low airflow velocities and high and low staticdifferential pressure applications.

The output end 14 is open to provide pneumatic communication between thepressure orifices 18 and a pressure sensor (e.g., transducer,manometer), for example through a flexible tube. The terminal end 16 isclosed to the atmosphere. Closed to the atmosphere means that theterminal end does not provide a communication path between pressureorifices 18 and the external atmosphere. For example, the terminal endmay be open and connected through additional piping (e.g., plastictubing) to a pressure sensor or otherwise not providing communicationwith the external atmosphere. For example, with reference to FIG. 4, theterminal end 16 may be connected (e.g., through conduit) to the pressuresensor 40. The terminal end 16 may be configured to engage with astructure (e.g., duct, cabinet, rail) to orient the pressure orifices inthe downstream direction relative to the airflow.

The tube 12 may be constructed of various materials in which thepressure orifices 18 can be formed and maintained in the desiredorientation during use. Non-limiting examples of tube 12 includealuminum tubing, such as 3003 or 6063 aluminum alloy, which provides arigid structure for orientation and corrosion resistance. Innon-limiting example, tube 12 is constructed of an aluminum alloy andhas an outside diameter (OD) of about 0.25 inches (e.g., OD tolerance+/−0.005 in.), an inside diameter (ID) of about 0.18 inches, and a wallthickness of about 0.035 inches. In another non-limiting example, tube12 is constructed of an aluminum alloy and has an outside diameter (OD)of about 0.25 inches (e.g., OD tolerance +/−0.025 in.), an insidediameter (ID) of about 0.120 inches, and a wall thickness of about 0.065inches (e.g., wall thickness tolerance +/−0.10 in.). Materials otherthan aluminum alloy or metal may be utilized.

The length of the axial run 20 (e.g., measurement run) may be selectedfor example to extend laterally across the airflow and the airflowchannel (e.g., duct) in which pressure is to be measured. The pressureorifices 18 are axially aligned and formed on the same side of the tube12, referred to as the downstream side 22. In accordance to aspects ofthe disclosure the downstream side 22 is on the opposite side, i.e.,about 180 degrees, from the upstream side 24. In use the tube 12 ispositioned in the airflow with the axial run 20 extending laterallyacross the airflow, shown by the arrow 26 in FIG. 2, with the upstreamside 24 oriented to face upstream into the direction of airflow 26 andthe downstream side 22 and pressure orifices 18 are oriented in thedownstream direction. For purposes of description, the direction of theairflow 26 is designated as North and on tube 12 (FIG. 2) theintersection of the direction of airflow 26 with the downstream side 22of the axial run of the tube and is designated as 0-degrees and theintersection of the axis of the airflow 26 with the upstream side 24 ofthe axial run is 180 degrees.

According to an aspect of the disclosure the pressure orifices 18 arepositioned on the downstream side 22 and are of a maximum diameter so asnot to extend into the airflow, i.e., the pressure orifices 18 arecontained within a range of about 180 degrees so as not to extendoutside of the circumference extending from about 90 degrees to 270degrees (−90 degrees) inclusive of the 0-degree designation. It has beenrealized that such an arrangement permits the accurate measurement ofstatic pressure in the airflow and reduces the clogging of the pressureorifices 18. According to aspects of the disclosure the pressure probe10 does not have any pressure orifices other than the pressure orifices18 that are axially aligned along the downstream side 22 of the axialrun 20. In contrast a traditional pressure probe (e.g., pitot statictube) that is utilized in duct-type systems has an axial sectionterminating at a nosepiece forming a total pressure hole and staticpressure holes that are formed on opposing sides of the axial sectionand oriented perpendicular to the nosepiece and the total pressure hole.In use the pitot static tube is positioned with the axial sectionparallel with the airflow so that the total pressure hole is orientedupstream and the static pressure holes are oriented perpendicular to theairflow direction and the static pressure holes are exposed to theairflow.

FIG. 3 is a non-limiting example of a pressure probe 10 constructed froma length of tubing. In this example, the pressure probe 10 wasconstructed from a linear length of 3003 series aluminum seamless tube12 having a 0.250 inch OD by 0.180 inch ID by 21 inches in length. Anaxial measurement run 20 of 18.75 inches was selected. Eighteen pressureorifices 18 having a diameter of about 0.063 inches were drilled throughthe downstream side 22 of the tube 12 with a spacing 28 of aboutone-inch between the adjacent pressure orifices 18. The terminal end 16is closed, for example by crimping. The terminal end 16 may also includean orientation structure 30 configured to mate with a respectivestructure of an airflow channel. In this example, the orientationstructure 30 is in the form of a flattened tab. The orientationstructure 30 is oriented relative to the downstream side 22 and thepressure orifices 18 so that when properly installed in an airflowchannel the pressure orifices 18 are oriented in the downstreamdirection relative to the airflow. In this example a bend is formed inthe tube 12 between the output end 14 and the axial run 20. Othermaterials of construction and dimensions may be utilized withoutdeparting from the scope of the disclosure.

According to an aspect of the disclosure, the pressure orifices 18 havea diameter 25 in the range of about 10 to 40 percent of the outsidediameter 27 of the axial run 20. According to an aspect of thedisclosure, the pressure orifices 18 have a diameter in the range ofabout 15 to 35 percent of the outside diameter of the axial run.According to an aspect of the disclosure, the pressure orifices 18 havea diameter in the range of about 20 to 30 percent of the outsidediameter of the axial run 20. According to an aspect of the disclosure,the pressure orifices 18 have a diameter in the range of 28 to 22percent of the outside diameter of the axial run. According to an aspectof the disclosure, the pressure orifices 18 have a diameter of about 25percent of the outside diameter of the axial run.

FIG. 4 illustrates a block diagram of an example of a climate controlsystem 32 for example a heating, ventilating and air conditioning (HVAC)system, incorporating a pressure probe 10 according to aspects of thedisclosure. The climate control system 32 includes a structure 34 (e.g.,duct, housing) forming an airflow channel 36 disposing a unit 38 acrosswhich the airflow 26 passes. Non-limiting examples of units 38 includeair filters, enthalpy wheels, and dampers. The airflow 26 is flowing inthe direction indicated by the solid arrows.

Climate control system 32 incorporates a pressure sensor 40 to measurethe pressure drop across the unit 38. The pressure sensor 40 may be aconventional pressure transducer that determines the static pressuredifference across the unit 38. The pressure sensor 40 may be for examplean analog or digital manometer having a first and a second pressureinput ports. The pressure sensor 40 includes a first pressure probe 10providing a first pressure input 42 and a second pressure probe 10providing a second pressure input 44. In FIG. 4 the first pressure input42 is located on the upstream side of the unit 38 relative to thedirection of airflow 26 and the second pressure input 44 is located onthe downstream side of the unit 38.

Each of the pressure probes 10 for the first and second pressure inputs42, 44 are oriented so that the axial run 20 extends laterally acrossthe airflow channel 36 with the upstream side 24 facing into airflow 26and the pressure orifices 18 oriented downstream so that the pressureorifices are on the backside of the pressure probe tube 12 shielded fromthe airflow 26. An orientation structure 30, for example at the terminalend of the pressure probe, may mate with a cooperative orientationstructure 46 (e.g., slot, rails, etc.) disposed with the structure 34 tofacilitate installing and maintaining the pressure probes in the desiredorientation.

With additional reference to FIG. 5, the pressure sensor 40 may beutilized for example in a monitoring system (e.g., method 100) toprovide feedback data to indicate conditions of the unit 38. Accordingto an aspect of the disclosure the climate control system 32 includes acontroller 48 that is coupled to the pressure sensor 40 to monitor thepressure sensor 40. The controller 48 may visually display or otherwisecommunicate to a human user or another controller the measureddifferential static pressure data and/or a condition of the unitassociated with the measured differential static pressure data. Thoughthe pressure sensor 40 is shown as a separate component from thecontroller 48, it should be understood that they may both beincorporated into a single unit. The controller 48 may have adiagnostics table stored in memory of the controller 48 for determiningconditions. The values in the table may be selected based on thedifferential static pressure properties, which may be known for exampleat the time of manufacture. The conditions of the unit 38 may includefor example a dirty filter or enthalpy wheel, a degree of a dirty filteror enthalpy wheel, and a filter or enthalpy wheel life value, such as aremaining enthalpy wheel or filter life value.

The controller 48 may include an interface 50 that may be configured toreceive and transmit the feedback data. The interface 50 may be aconventional interface that is used to communicate (i.e., receive and ortransmit) data. The controller 48 may also include additional componentstypically included within a controller for a HVAC unit, such as a powersupply or power port.

The illustrated controller 48 also includes a processor 52 and a memory54. The memory 54 may be a conventional memory typically located withina microcontroller that is constructed to store data and computerprograms. The memory 54 may store operating instructions to direct theoperation of the processor 52 when initiated thereby. The operatinginstructions may correspond to algorithms that provide the functionalityof the schemes disclosed herein. The processor 52 may be a conventionalprocessor such as a microprocessor. The interface 50, processor 52 andmemory 54 may be coupled together via conventional means to communicateinformation.

FIG. 5 illustrates a flow diagram of a method 100 of monitoring acondition of a unit 38 in a climate control system 32 according toaspects of the disclosure. With additional reference to FIGS. 1-4, themethod 100 begins at a block 105 at the start-up of a climate controlsystem, e.g. climate control system 32. Differential static pressuredata of airflow across a unit 38 disposed in a climate control system isobtained at block 110. The differential static pressure data may beobtained by a first pressure probe 10 positioned upstream of the unitand a second pressure probe 10 positioned downstream of the unit,wherein each of the first and the second pressure probes include a tubehaving an output end, a closed terminal end, and an axial run 20, andpressure orifices 18 axially aligned along a downstream side 22 of theaxial run, wherein the axial run is positioned laterally across theairflow channel and the downstream side and the pressure orifices areoriented in the downstream direction. A controller 48 receives (block120) the differential static pressure data from the pressure sensor 40.The controller may determine (block 130) a condition of the unit basedon the differential static pressure across the unit. At block 140 thecontroller communicates the unit condition.

The term “substantially,” “approximately,” and “about” is defined aslargely but not necessarily wholly what is specified (and includes whatis specified; e.g., substantially 90 degrees includes 90 degrees andsubstantially parallel includes parallel), as understood by a person ofordinary skill in the art.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the disclosure.Those skilled in the art should appreciate that they may readily use thedisclosure as a basis for designing or modifying other processes andstructures for carrying out the same purposes and/or achieving the sameadvantages of the embodiments introduced herein. Those skilled in theart should also realize that such equivalent constructions do not departfrom the spirit and scope of the disclosure, and that they may makevarious changes, substitutions and alterations herein without departingfrom the spirit and scope of the disclosure. The scope of the inventionshould be determined only by the language of the claims that follow. Theterm “comprising” within the claims is intended to mean “including atleast” such that the recited listing of elements in a claim are an opengroup. The terms “a,” “an” and other singular terms are intended toinclude the plural forms thereof unless specifically excluded.

What is claimed is:
 1. A pressure probe, comprising: a tube positionedin an airflow channel of a climate control system, the tube comprising afirst end, a second end, an internal passage and an axial run; aplurality of pressure orifices formed on a same side of the tube alongthe axial run; and wherein the plurality of pressure orifices comprise amaximum diameter that does not extend into an airflow.
 2. The pressureprobe of claim 1, wherein the plurality of pressure orifices are axiallyaligned along a downstream side of the axial run.
 3. The pressure probeof claim 2, wherein: an upstream side of the axial run opposite from thedownstream side of the axial run does not comprise a pressure orifice;and the plurality of pressure orifices on the downstream side arepositioned opposed to the airflow and in an arrangement to obtain staticpressure in the airflow.
 4. The pressure probe of claim 2, wherein theplurality of pressure orifices are equally spaced from one another alongthe downstream side of the axial run.
 5. The pressure probe of claim 1,wherein the first end comprises a terminal end that is closed to theatmosphere.
 6. The pressure probe of claim 1, wherein the first end isconfigured to engage with a structure to orient the plurality ofpressure orifices in a downstream direction relative to the airflow. 7.The pressure probe of claim 1, wherein the second end comprises anoutput end that is open to the atmosphere to provide pneumaticcommunication between the plurality of pressure orifices and a pressuresensor.
 8. The pressure probe of claim 7, wherein the pressure sensorcomprises at least one of a transducer and a manometer.
 9. The pressureprobe of claim 1, wherein the tube is rigid.
 10. The pressure probe ofclaim 1, wherein the plurality of pressure orifices have a diameter of10 to 40 percent of an outside diameter of the axial run.
 11. Thepressure probe of claim 1, wherein the plurality of pressure orificeshave a diameter of 20 to 30 percent of an outside diameter of the axialrun.
 12. The pressure probe of claim 1, wherein the plurality ofpressure orifices have a diameter of 25 percent of an outside diameterof the axial run.
 13. The pressure probe of claim 1, wherein: the axialrun has an outside diameter of 0.250 inches; and the plurality ofpressure orifices have a diameter of 15 to 35 percent of an outsidediameter of the axial run.
 14. The pressure probe of claim 1, wherein:the axial run has an outside diameter of 0.250 inches; and the pluralityof pressure orifices have a diameter of 25 percent of an outsidediameter of the axial run.
 15. A pressure probe, comprising: a tubepositioned in an airflow channel of a climate control system, the tubecomprising a first end, a second end, an internal passage and an axialrun; a plurality of pressure orifices formed on a same side of the tubealong the axial run and comprise a maximum diameter that does not extendinto an airflow; and wherein the axial run extends laterally across theairflow and the airflow channel in which pressure is to be measured. 16.The pressure probe of claim 15, wherein the plurality of pressureorifices are axially aligned along a downstream side of the axial run.17. The pressure probe of claim 16, wherein: an upstream side of theaxial run opposite from the downstream side of the axial run does notcomprise a pressure orifice; and the plurality of pressure orifices onthe downstream side are positioned opposed to the airflow and in anarrangement to obtain static pressure in the airflow.
 18. The pressureprobe of claim 16, wherein the plurality of pressure orifices areequally spaced from one another along the downstream side of the axialrun.
 19. The pressure probe of claim 15, wherein the first end comprisesa terminal end that is closed to the atmosphere.
 20. The pressure probeof claim 15, wherein the second end comprises an output end that is opento the atmosphere to provide pneumatic communication between theplurality of pressure orifices and a pressure sensor.